The Election Commission of Nepal has said that it is not yet ready to hold polls set for June under a peace deal agreed with former Maoist rebels.
The prime minister (left) will serve alongside Maoists
The commission say that it needs more time to draft new laws before polling can take place.
The government and the Maoists agreed last year that voting should take place on 20 June to elect a special assembly and write a new constitution.
But the commission says that the country is not sufficiently secure.
It says that ongoing ethnic unrest in the south - which has left at least 60 people dead - has hampered election plans.
The Maoists have emerged as a major political force
"Technically it will be very difficult to hold the constituent assembly elections by June," election commissioner Bhojraj Pokharel told the AFP news agency.
"The date set by the government is just over 60 days away, and we have already told the government that we need at least 110 days to prepare for the election after necessary legislation has been passed," Mr Pokharel said.
"The peace and security situation has not yet improved in the country," he added in a separate statement.
"We cannot ignore the fact that it could create difficulties if the nation opts to hold polls without addressing this issue."
There are presently 205 constituencies in Nepal electing the same number of representatives to the national legislature.
Mr Pokharel's statement came just before a meeting between the government and representatives of the eight ruling alliance partners to discuss an election schedule.
Maoist rebels gave up their armed revolt - in which 13,000 people died - last year and joined a peace process with the government.
They have locked up their arms in seven UN monitored camps and confined their fighters to barracks.